Conventionally, titanium (Ti)-nickel (Ni)-based alloys are widely known as alloy materials used for medical guidewires, medical stents and the like. However, in recent years, attention is given to titanium (Ti)-tantalum (Ta)-based alloys containing no Ni that may cause allergies in a living body.
For example, Japanese Patent No. 4302604 proposes a Ti—Ta-based alloy containing one or both of tantalum (Ta) and niobium (Nb) in prescribed amounts and further containing 1 to 20 mol % of zirconium (Zr) and 1 to 6 mol % of molybdenum (Mo), wherein the total amount of Ta, Nb, Zr, and Mo is 60 mol % or less with the balance being Ti and unavoidable impurities. This Ti—Ta-based alloy contains no Ni and is therefore highly safe for the human body. Other features of the alloy are that it has superelasticity and high cold workability and therefore has high productivity.